A method for the identification of guinea pig blood meal in the Chagas disease vector, Triatoma infestans.

Background: In a SINE-based PCR assay, a primer set specific for guinea pig genome short interspersed elements DNA was used to test the utility of genomic markers for identifying the source of vertebrate blood meals of Triatoma infestans.

Methods: The investigation consisted of two assays. In Assay 1, thirty-six insects, collected from the Province of Zudáñez in Chuquisaca, Bolivia were frozen 1-40 hours after feeding, under controlled conditions, on guinea pigs. The species of the vertebrate host was confirmed from dissection of the posterior part of the abdomen of each insect followed by DNA extraction and PCR amplification. Assay 2 investigated whether the technique worked under field conditions. We analyzed the bloodmeal of 34 insects collected from households and peri-domestic structures from communities where wild and captive guinea pigs occur. After collection, the insects were maintained at room temperature for 2 months without feeding and then analyzed.

Results: In Assay 1, each of the 36 insects allowed to feed on guinea pig blood tested positive for guinea pig DNA. The guinea pig DNA was reliably identified in as little as 1 hour and up to 40 hours after feeding. For Assay 2, 8 out of the 34 samples (23%) showed positive results with guinea pig specific primers.

Conclusion: The results in assay 1 demonstrated that DNA from the vertebrate host can be amplified 1-40 hours post feeding from the abdomen of the blood-feeding Chagas disease vector Triatoma infestans. The results in assay 2 confirmed that the procedure works on insects collected from households and peri-domestic structures and that the source of a blood meal can be determined at least 2 months post feeding.